Carbon and nitrogen content based estimation of the fat content of animal carcasses in various species

The objective of this study was to explore whether the C and N content can be used to estimate the fat content of animal carcasses. Considering the mean C and N contents of body fat and body protein, the fat content (EE) [%] can be predicted from C and N values [%] according to the generally valid equation EE=1.3038·C – 4.237·N. The application of this equation to estimate the total fat content of all animal carcasses results in significant differences in fat content between predicted and measured values. Therefore, we derived specific equations for rats, pigs, cattle, sheep, broilers and mice to predict the fat content by dual linear regression analysis (y=EE [% DM], x₁=C [% DM], x₂=N [% DM]) based on measured fat, C, and N contents of animal body samples. The specific equations for different animals showed residual standard deviations of 1.55, 1.63, 1.12, 1.35, 1.85 and 0.92% fat for rats, pigs, cattle, sheep, broilers and mice, respectively.     

Determination of polyphenol and crude nutrient content and nutrient digestibility of dried and ensiled white and red grape pomace cultivars

The present study aimed to determine the nutrient and energy content of fresh and ensiled grape pomace (GP) from different grape varieties originating from Germany, and to estimate the feed value of dried white, dried red and ensiled white GP by calculating nutrient digestibility and the content of metabolisable energy (ME) and net energy lactation (NEL) measured in sheep as a ruminant model. GP from red cultivars had higher contents of organic matter (OM), crude protein (CP), ether extract (EE), crude fibre (CF), total phenolic contents (TPC) and ME, whereas the concentrations of ash and sugar were lower than from white cultivars. Compared with untreated GP, ensiled GP had increased concentrations of CP (+19%), ether extract (EE; +23%) and CF (+12%) and a higher ME content (+7%) and markedly decreased concentrations of sugar (?99.6%) and TPC (?48%). The concentrations of dry matter, OM and ash were not different between ensiled and fresh GP. Compared with dried GP, ensiled GP had a higher nutrient digestibility (OM, +32%; CP, +43%; CF, +46%; neutral detergent fibre [NDF], +54%; acid detergent fibre [ADF], +69%) and higher energy values (ME, +16%; NEL, +19%). The digestibility of OM, CP, EE and CF and the energy content were higher for dried red than for dried white GP, whereas the digestibility of NDF_OM and ADF_OM was lower for dried red than dried white GP. In conclusion, the results show that both red and white GP are suitable dietary sources for enrichment with TPC. Furthermore, compared with drying ensiling of GP improves the feeding value of GP and is a good possibility of preserving the seasonally produced by-product of winemaking for ruminant feeding.     

Accuracy of predicting chemical body composition of growing pigs using dual-energy X-ray absorptiometry

Studies in animal science assessing nutrient and energy efficiency or determining nutrient requirements benefit from gathering exact measurements of body composition or body nutrient contents. Those are acquired by standardized dissection or by grinding the body followed by wet chemical analysis, respectively. The two methods do not result in the same type of information, but both are destructive. Harnessing human medical imaging techniques for animal science can enable repeated measurements of individuals over time and reduce the number of individuals required for research. Among imaging techniques, dual-energy X-ray absorptiometry (DXA) is particularly promising. However, the measurements obtained with DXA do not perfectly match dissections or chemical analyses, requiring the adjustment of the DXA via calibration equations. Several calibration regressions have been published, but comparative studies of those regression equations and whether they are applicable to different data sets are pending. Thus, it is currently not clear whether existing regression equations can be directly used to convert DXA measurements into chemical values or whether each individual DXA device will require its own calibration. Our study builds prediction equations that relate body composition to the content of single nutrients in growing entire male pigs (BW range 20–100 kg) as determined by both DXA and chemical analyses, with R² ranging between 0.89 for ash and 0.99 for water and CP. Moreover, we show that the chemical composition of the empty body can be satisfactorily determined by DXA scans of carcasses, with the prediction error ranging between 4.3% for CP and 12.6% for ash. Finally, we compare existing prediction equations for pigs of a similar range of BWs with the equations derived from our DXA measurements and evaluate their fit with our chemical analysis data. We found that existing equations for absolute contents that were built using the same DXA beam technology predicted our data more precisely than equations based on different technologies and percentages of fat and lean mass. This indicates that the creation of generic regression equations that yield reliable estimates of body composition in pigs of different growth stages, sexes and genetic breeds could be achievable in the near future. DXA may be a promising tool for high-throughput phenotyping for genetic studies, because it efficiently measures body composition in a large number and wide array of animals.     

Prediction of the energy value of rabbit feeds varying widely in fibre content

Digestibility trials of 23 pelleted diets, with one or two ingredients and having 8.7–53.5% acid detergent fibre (ADF) on a dry matter (DM) basis, were carried out in adult rabbits fed ad libitum. Using a step-wise linear regression approach, the relationship between the digestible energy content (DE) or the coefficient of digestibility of gross energy (dGE) and the chemical composition of diets was established. Excluding beet pulp, with a very high crude fibre digestibility (54.8%), the prediction equations obtained were: DE (MJ kg⁻¹ DM) = 14.2 − 0.205 ADF + 0.218 EE + 0.057 CP (R² = 0.965, RSD = 0.494) and dGE (%) = 83.2 − 1.07 ADF (R² = 0.951, RSD = 3.15) where ADF, ether extract (EE) and crude protein (CP) are expressed as a percentage on a DM basis. When diets with level of EE or CP higher than 6% or 18% respectively (grape marc, olive oil cake, brewer's grains, sunflower meal) were also removed, the prediction equations became: DE = 15.9 − 0.219 ADF (R² = 0.974, RSD = 0.391) and dGE = 85.6 − 1.20 ADF (R² = 0.977, RSD = 2.02). The contents in DE, digestible crude protein and undigestible crude fibre of 21 ingredients are presented and discussed in comparison with other studies.     

Determination and prediction of the digestible and metabolisable energy content of barley for growing pigs based on chemical composition

This experiment was conducted to define the sources of variation determining the energy content of barley and to develop a practical method to predict the digestible energy (DE) and metabolisable energy (ME) content of individual barley samples. The 19 barley samples used in this study were diverse varieties grown in different regions. The feeding experiment used 57 barrows (initial body weight 31.5 ± 3.2 kg) and was conducted over two consecutive periods (n = 6 per treatment) using a completely randomised design. During each period, the pigs were placed in metabolic crates for a 5-d total collection of faeces and urine following a 10-d adaptation to the diets. Among the barley samples, on dry matter (DM) basis the levels of neutral detergent fibre, acid detergent fibre (ADF), crude protein and starch ranged from 16.1% to 38.9%, 3.9% to 9.6%, 10.1% to 16.8% and 43.5% to 57.9%, respectively. The mean determined DE and ME contents amounted to 14.7 and 14.4 MJ/kg DM and varied among the samples by 1.85 MJ (13.6%) and 1.78 MJ (13.3%), respectively. The ADF fraction accounted for 73% and 76% of the total variation in the DE and ME content, respectively. It revealed that for prediction of the DE and ME contents in barley, equations had the best fit when the analysed contents of ADF, neutral detergent fibre and gross energy were used for calculation (R² = 0.92). On the basis of the developed equations, the DE and ME contents of barley of different origin can be predicted with an acceptable accuracy when used as feed for growing pigs.     

Feeding value of crambe press cake and extracted meal as well as production responses of growing-finishing pigs and dairy cows fed these by-products

To analyse the feeding value of crambe press cake (CPC) and crambe extracted meal (CEM), and the incorporation limits in pig diets, a series of balance trials with a total of 12 male castrates was conducted. Additionally, in a feeding trial the effect of 5% and 10% CPC or CEM on growth performance and on pork quality was tested. The CP content of CPC and CEM was 207 and 331 g/kg DM, respectively, and the residual EE 144 and 26 g/kg DM, respectively. The erucic acid concentration amounted to 56% of total fatty acids. Glucosinolate contents were found to be 50 mmol/kg CPC-DM and 70 mmol/kg CEM-DM. The digestibility of OM was 54% for both by-products and the ME contents were 10.6 and 9.3 MJ/kg DM for CPC and CEM, respectively. In the feeding trial, 10% CPC in the diet significantly decreased BWG from 782 g/d (controls) to 742 g/d. Due to glucosinolate intake, the weight of liver, thyroid glands and kidneys was significantly increased. The body fat showed an increased deposition of erucic acid in back fat and intramuscular fat, but changes in sensory properties of the meat were not detected. It is recommended that the incorporation rate of CPC and CEM in diets for growing-finishing pigs should not exceed 5%. The balance experiments, carried out with four wethers each, showed that the OM of CPC and CEM was better digested by ruminants, amounting to 71% or 67%, respectively. The energy content amounted to 7.4 and 6.0 MJ NEL/kg DM, respectively. In the feeding trials with lactating cows, 30% CPC or CEM in the concentrate resulted in a decrease of concentrate intake of about 7%. Due to the high residual fat content of CPC, the milk fat content decreased and the erucic acid content increased. The high glucosinolate intake affected the iodine concentration in the milk. CPC and CEM feeding decreased the iodine content from 271-117 microg/kg and from 182-77 microg, respectively. It is recommended that crambe by-products should not exceed 15% in concentrates or an intake of 1 kg/d for dairy cows.     

Prevalence of Gastrointestinal Clostridium difficile Carriage in Australian Sheep and Lambs

Recently, Clostridium difficile has been isolated from a wide variety of animals, particularly production animals, mainly cattle and pigs. Concurrently, the incidence of C. difficile infection (CDI) in humans has increased in the community, with some suggestions that food-borne transmission of C. difficile is occurring. Interestingly, sheep and lambs appear not to have been investigated for carriage/colonization with C. difficile. The aim of this project was to determine the prevalence of carriage of C. difficile in sheep and lambs in Australia by culturing fecal samples. A total of 371 sheep and lamb fecal samples were received in seven batches from three different geographic areas in eastern Australia and two in Western Australia. The overall rate of detection in sheep and lambs was low (4.0%); however, carriage/colonization in lambs (6.5%) was statistically significantly higher than that in sheep (0.6%) (P = 0.005). Seven distinct PCR ribotype patterns were observed, three of which were known international ribotypes (UK 056 [n = 1], UK 101 [n = 6], and UK 137 [n = 2]), while the remainder were unable to be matched with our available reference library. This low rate of carriage/colonization in Australian ovines suggests they are unlikely to be a major source/reservoir of human infections.     

Genetic trends of abdominal fat content in a male broiler chicken line

Data of chickens from a broiler-breeding program were collected and used to determine the genetic trends of absolute and relative abdominal fat content. The genetic trends were estimated by the regression of trait genetic value averages on hatch-years. Genetic values from 32,485 individuals were used for regression analysis. The genetic trend estimate for absolute abdominal fat content was +0.39 g per year, indicating that abdominal fat deposition in the analyzed line, in absolute terms, tended to increase, making the existing excess fat deposition in the broilers even worse. However, the genetic trend of relative abdominal fat content was not significant, indicating that there is no increase on abdominal fat content when it is corrected for body weight.     

Determination of optimum fat intake

In a 14-day experiment, adult rats weighting 250-260 g were given ad libitum diets with a constant protein content [casein - 10 %] and a mounting fat content [margarine - 0, 10, 20, 30 and 40 % - added at the expense of carbohydrates]. The growth parameters of protein biological value - PER and NPR - were determined and together with weight increments in correlation to protein an fat intake [a linear correlation] they were used on the basis of their regression equations to calculate the reciprocal relationships of fat and protein intake [for equality y]. By substituting the optimum protein intake [43.3 g/14 days - according to NPU], the optimum fat intake for adult rats was found to correspond to dietary fat concentrations of 9.72 % [y = weight increments], 12,82 % [y = PER] and 11.83 % [y = NPR]. These results wee verified in a biological experiment in which adult animals, for 14 days, were given a limited amount [31 g/animal per day] of diets containing 10 % protein [casein] an d9, 10, 11, 12, and 13 % fat [margarine - at the expense of carbohydrates] with the aim of studying the effect of a mounting fat intake on optimum protein intake [43.4 g/14 days]. The correctness of the mathematical method for determining the optimum fat intake was verified by a biological method [the optimum net protein utilization , NPU, which is highest in diets containing 11 % fats, i.e. 22.5 % of the total energy value of the diet]. It was also found that this method, both along and in conjunction with other methods [especially the one using the NPR parameter], was suitable for the determination of optimum nutrient values.     

Feeding value of crambe press cake and extracted meal as well as production responses of growing-finishing pigs and dairy cows fed these by-products

To analyse the feeding value of crambe press cake (CPC) and crambe extracted meal (CEM), and the incorporation limits in pig diets, a series of balance trials with a total of 12 male castrates was conducted. Additionally, in a feeding trial the effect of 5 % and 10 % CPC or CEM on growth performance and on pork quality was tested. The CP content of CPC and CEM was 207 and 331?g/kg DM, respectively, and the residual EE 144 and 26?g/kg DM, respectively. The erucic acid concentration amounted to 56 % of total fatty acids. Glucosinolate contents were found to be 50?mmol/kg CPC-DM and 70?mmol/kg CEM-DM. The digestibility of OM was 54 % for both by-products and the ME contents were 10.6 and 9.3 MJ/kg DM for CPC and CEM, respectively. In the feeding trial, 10 % CPC in the diet significantly decreased BWG from 782?g/d (controls) to 742?g/d. Due to glucosinolate intake, the weight of liver, thyroid glands and kidneys was significantly increased. The body fat showed an increased deposition of erucic acid in back fat and intramuscular fat, but changes in sensory properties of the meat were not detected. It is recommended that the incorporation rate of CPC and CEM in diets for growing-finishing pigs should not exceed 5 %.

The balance experiments, carried out with four wethers each, showed that the OM of CPC and CEM was better digested by ruminants, amounting to 71% or 67%, respectively. The energy content amounted to 7.4 and 6.0 MJ NEL/ kg DM, respectively.

In the feeding trials with lactating cows, 30 % CPC or CEM in the concentrate resulted in a decrease of concentrate intake of about 7%. Due to the high residual fat content of CPC, the milk fat content decreased and the erucic acid content increased. The high glucosinolate intake affected the iodine concentration in the milk. CPC and CEM feeding decreased the iodine content from 271?– 117?μg/kg and from 182?– 77?μg, respectively. It is recommended that crambe by-products should not exceed 15 % in concentrates or an intake of 1?kg/d for dairy cows.     

Relationships between anthropometric, body composition and bone mineral parameters in 7-8-year-old rhythmic gymnasts compared with controls

The aim of the study was to investigate the relationships between specific anthropometric (9 skinfolds, 13 girths, 8 lengths and 8 breadths), body composition (body fat %, fat free mass [FFM], fat mass [FM]) parameters and bone mineral parameters (bone mineral density [BMD], bone mineral content [BMC) in young rhythmic gymnasts and same age controls. Eighty nine 7-8-year-old girls participated in this study and were divided to the rhythmic gymnast's (n = 46) and control (n = 43) groups. Body composition was determined by dual energy X-ray absorptiometry (FFM, FM, body fat %, BMD and BMC). Body fat % and FM were lower and BMD and BMC values at lumbar spine (L2-L4) and femoral neck were higher in rhythmic gymnasts compared with controls. All measured skinfold thicknesses were thicker in controls. In girths, lengths and widths there were only few significant differences between the groups. Stepwise multiple regression analysis indicated that skinfold thicknesses (supraspinale and medial calf) influenced L2-L4 BMD only in controls 38.2% (R2x100). Supraspinale and iliac crest skinfold thicknesses characterised L2-L4 BMC 43.9% (R2x100). Calf girths influenced BMD in L2-L4 52.3% (R2x100) in controls. BMC in L2-L4 was dependent only on mid-thigh girths 35.9% (R2x100). BMD in L2-L4 was dependent on tibiale-laterale height 30.0% (R2x100). Biiliocristal breadths together with sitting height characterised BMC in L2-L4 BMD 62.3% (R2x100). In conclusion, we found that the relationships between anthropometry, body composition and bone parameters in young rhythmic gymnasts are weak. In control group first of all lower body anthropometric parameters significantly correlated with BMD and BMC in spine.     

Interspecies differences in the empty body chemical composition of domestic animals

Domestication of animals has resulted in phenotypic changes by means of natural and human-directed selection. Body composition is important for farm animals because it reflects the status of energy reserves. Thus, there is the possibility that farm animals as providers of food have been more affected by human-directed selection for body composition than laboratory animals. In this study, an analysis was conducted to determine what similarities and differences in body composition occur between farm and laboratory animals using literature data obtained from seven comparative slaughter studies (n = 136 observations). Farm animals from four species (cattle, goats, pigs and sheep) were all castrated males, whereas laboratory animals from three species (dogs, mice and rats) comprised males and/or females. All animals were fed ad libitum. The allometric equation, Y = aX^b, was used to determine the influence of species on the accretion rates of chemical components (Y, kg) relative to the growth of the empty body, fat-free empty body or protein weights (X, kg). There were differences between farm and laboratory animals in terms of the allometric growth coefficients for chemical components relative to the empty BW and fat-free empty BW (P < 0.01); farm animals had more rapid accretion rates of fat (P < 0.01) but laboratory animals had more rapid accretion rates of protein, water and ash (P < 0.01). In contrast, there was no difference in terms of the allometric growth coefficients for protein and water within farm animals (P > 0.2). The allometric growth coefficients for ash weight relative to protein weight for six species except sheep were not different from a value of 1 (P > 0.1), whereas that of sheep was smaller than 1 (P < 0.01). When compared at the same fat content of the empty body, the rate of change in water content (%) per unit change in fat content (%) was not different (P > 0.05) across farm animal species and similar ash-to-protein ratios were obtained except for dogs. The fraction of empty body energy gain retained as fat increased in a curvilinear manner, and there was little variation among farm animals at the same fat content of the empty body. These findings may provide the opportunity to develop a general model to predict empty body composition across farm animal species. In contrast, there were considerable differences of chemical body composition between farm and laboratory animals.     

Predicting the chemical composition of the body and the carcass of hair sheep using body parts and carcass measurements

Determination of the chemical composition in the body and carcass of ruminants is important for both nutritional requirement studies and the meat industry. This study aimed to develop equations to predict the body and carcass chemical composition of hair sheep using the chemical composition of body parts, carcass measurements and shrunk BW as predictors. A database containing 107 individual records for castrated male hair sheep ranging from 24 to 43 kg BW was gathered from two body composition studies. The empty body, carcass and body parts were analyzed for water, ash, fat and protein contents (%). The body parts used to estimate body and carcass composition were fore leg, hind leg and 9–11th rib section. The carcass measurements used were leg length, thoracic circumference, hind circumference, hind width, thoracic width, thoracic depth and chest width. Each model performance was evaluated using a leave-one-out cross-validation. Multiple regression analysis considering the study as a random effect revealed that body parts in association with carcass measurements were significant for predicting the chemical composition in the body of castrate male sheep. However, the use of the chemical composition of hind leg produced the best models for predicting the ash and fat contents in the empty body, whereas the water and protein contents in the empty body were better predicted when using the chemical compositions of 9–11th rib section and fore leg, respectively. Multiple regression analysis also revealed that most body parts were suitable for predicting the carcass composition, except for 9–11th rib section whose chemical composition did not produce significant prediction equations for ash and protein carcass contents. The use of the chemical composition of hind leg in association with carcass measurements produced the best models for predicting the water and fat contents in the carcass, while the ash and protein contents in the carcass were better predicted when using the chemical composition of fore leg. In conclusion, precision, accuracy and goodness-of-fit of the equations drove the selection of the chemical composition of hind leg and carcass measurements in a multivariate approach, as the most suitable predictors of the chemical composition of the body and carcass of hair sheep. However, the chemical composition of fore leg may be used as well. The developed equations could improve the accuracy of the empty body and carcass composition estimations in sheep, optimizing the estimation of nutrient requirements, as well as the carcass quality evaluation for this species.     

Prevalence and distribution of Arcobacter species in various sources in Turkey and molecular analysis of isolated strains by ERIC-PCR

AIMS: To determine the prevalence of Arcobacter in various food, animal and water sources in Turkey and to subtype the isolated strains using enterobacterial repetitive intergenic consensus (ERIC)-PCR. METHODS AND RESULTS: A total of 806 samples consisting of chicken (100) and turkey meat (100); minced beef (27); rectal swabs from cattle (173), sheep (68) and dogs (62); cloacal swabs of broilers (100) and layers (100); gall bladders of cattle (50) and drinking water samples (26) were examined. A previously described membrane filtration method was used for the isolation. Isolates were identified at species level using multiplex-PCR and discriminated by ERIC-PCR for subtyping. Ninety-eight (12.1%) of the samples examined were found positive for arcobacters. Arcobacter spp. were isolated from 68%, 4%, 6.9%, 8% and 37% of chicken and turkey meats, rectal swabs and gall bladders of cattle and minced beef, respectively. No arcobacters were obtained from the rectal swabs of sheep and dogs, cloacal swabs of broilers and layers, and water samples examined. In total, 99 Arcobacter isolates were obtained. Of these isolates, 92 were identified as Arcobacter butzleri, five were Arcobacter skirrowii and two were Arcobacter cryaerophilus. Thirteen distinct DNA profiles among A. butzleri isolates were obtained by the ERIC-PCR. Of these profiles, eight were from chicken carcass, three from cattle rectal swab and two from minced beef meat isolates. Some of the isolates originated from different sources gave the same DNA profiles. All isolates of A. skirrowii and A. cryaerophilus gave different DNA profiles. CONCLUSIONS: Poultry carcasses, minced beef meat, rectal swabs and gall bladders of cattle were found to be positive for Arcobacter spp. A. butzleri was the predominant species isolated. In addition, large heterogeneity among the Arcobacter isolates was determined. SIGNIFICANCE AND IMPACT OF THE STUDY: Contamination of the poultry carcasses and minced beef meat, rectal and gall bladder samples of cattle with arcobacters poses a risk for both human and animal infections. Detection of several different Arcobacter strains may suggest multiple sources for contamination and infection.     

Predicting the carcass chemical composition and describing its growth in live pigs of different sexes using computed tomographys

The aims of this study were (1) to evaluate the ability of computed tomography (CT) to predict the chemical composition of live pigs and carcasses, (2) to compare the chemical composition of four different sex types at a commercial slaughter weight and (3) to model and evaluate the chemical component growth of these sex types. A total of 92 pigs (24 entire males (EM), 24 surgically castrated males (CM), 20 immunocastrated males (IM) and 24 females (FE)) was used. A total of 48 pigs (12 per sex type) were scanned repeatedly in vivo using CT at 30, 70, 100 and 120 kg and slaughtered at the end of the experiment. The remaining 44 were CT scanned in vivo and slaughtered immediately: 12 pigs (4 EM, 4 CM and 4 FE) at 30 kg and 16 pigs each at 70 kg and 100 kg (4 per sex type). The left carcasses were CT scanned, and the right carcasses were minced and analysed for protein, fat, moisture, ash, Ca and P content. Prediction equations for the chemical composition were developed using Partial Least Square regression. Allometric growth equations for the chemical components were modelled. By using live animal and carcass CT images, accurate prediction equations were obtained for the fat (with a root mean square error of prediction (RMSEP_CV) of 1.31 and 1.34, respectively, and R²=0.91 for both cases) and moisture relative content (g/100 g) (RMSEP_CV=1.19 and 1.38 and R²=0.94 and 0.93, respectively) and were less accurate for the protein (RMSEP_CV=0.65 and 0.67 and R²=0.54 and 0.63, respectively) and mineral content (RMSEP_CV from 0.28 to 1.83 and R² from 0.09 to 0.62). Better equations were developed for the absolute amounts of protein, fat, moisture and ash (kg) (RMSEP_CV from 0.26 to 1.14 and R² from 0.91 to 0.99) as well as Ca and P (g) (RMSEP_CV=144 and 71, and R²=0.76 to 0.66, respectively). At 120 kg, CM had a higher fat and lower moisture content than EM. For protein, CM and IM had lower values than FE and EM. The ash content was higher in EM and IM than in FE and CM, while IM had a higher Ca and P content than the others. The castrated animals showed a higher allometric coefficient for fat and a lower one for moisture, with IM having intermediate values. However, for the Ca and P models, IM presented higher coefficients than EM and FE, and CM were intermediate.     

Interethnic differences in muscle, liver and abdominal fat partitioning in obese adolescents

The prevalence of insulin resistance and type 2 diabetes (T2D) in obese youth is rapidly increasing, especially in Hispanics and African Americans compared to Caucasians. Insulin resistance is known to be associated with increases in intramyocellular (IMCL) and hepatic fat content. We determined if there are ethnic differences in IMCL and hepatic fat content in a multiethnic cohort of 55 obese adolescents. We used (1)H magnetic resonance spectroscopy (MRS) to quantify IMCL levels in the soleus muscle, oral glucose tolerance testing to estimate insulin sensitivity, magnetic resonance imaging (MRI) to measure abdominal fat distribution. Liver fat content was measured by fast-MRI. Despite similar age and % total body fat among the groups, IMCL was significantly higher in the Hispanics (1.71% [1.43%, 2.0%]) than in the African-Americans (1.04% [0.75%, 1.34%], p = 0.013) and the Caucasians (1.2% [0.94%, 1.5%], p = 0.04). Liver fat content was undetectable in the African Americans whereas it was two fold higher than normal in both Caucasians and Hispanics. Visceral fat was significantly lower in African Americans (41.5 cm(2) [34.6, 49.6]) and was similar in Caucasians (65.2 cm(2) [55.9, 76.0]) and Hispanics (70.5 cm(2) [59.9, 83.1]). In a multiple regression analysis, we found that ethnicity independent of age, gender and % body fat accounts for 10% of the difference in IMCL. Our study indicates that obese Hispanic adolescents have a greater IMCL lipid content than both Caucasians and African Americans, of comparable weight, age and gender. Excessive accumulation of fat in the liver was found in both Caucasian and Hispanic groups as opposed to virtually undetectable levels in the African Americans. Thus, irrespective of obesity, there seem to be some clear ethnic differences in the amount of lipid accumulated in skeletal muscle, liver and abdominal cavity.     

Temporal variation and host association in the Campylobacter population in a longitudinal ruminant farm study

Campylobacter jejuni and C. coli were quantified and typed, using multilocus sequence typing (MLST), from fecal samples collected from a mixed cattle and sheep farm during summer. Cattle had a significantly higher prevalence than sheep (21.9% [74/338] and 14.0% [30/214], respectively), but both decreased over time. There were no differences in the average Campylobacter concentrations shed by cattle (600 CFU g(-1)) and sheep (820 CFU g(-1)), although sheep did show a significant temporal reduction in the number of Campylobacter organisms shed in their feces. A total of 21 different sequence types (STs) (97.7% C. jejuni, 2.3% C. coli) were isolated from cattle, and 9 different STs were isolated from sheep (40.6% C. jejuni, 59.4% C. coli). The Campylobacter population in cattle was relatively stable, and the frequencies of genotypes isolated showed little temporal variation. However, the composition of subtypes isolated from sheep did show significant temporal differences. The cattle and sheep consistently showed significant differences in their carriage of Campylobacter species, STs, and CCs despite the fact that both were exposed to the same farming environment. This work has highlighted the patterns of a Campylobacter population on a ruminant farm by identifying the existence of both temporal and between-host variations.     

Effect of ambient temperature on nutrient digestibility and nitrogen balance in sheep fed brown-midrib maize silage

The aim of the experiment was to determine the impact of heat stress on nutrient digestibility and nitrogen balance in sheep fed silages differing in fibre quality. The digestibility trial was conducted at three different ambient temperatures (15°C, 25°C and 35°C for 24 h/d). The tested brown-midrib maize (Bm) silage had a higher nutrient digestibility, except for ether extract (EE) and a higher metabolisable energy (ME) content than the control maize (Con) silage. Nitrogen (N) excretion with faeces was higher but N excretion with urine was lower for sheep fed Bm silage, subsequently N balance did not differ between the two silages. Temperature had no effect on nutrient digestibility, except for crude protein (CP), but N excretion with urine was lower at elevated temperatures. A diet by temperature interaction was found for dry matter (DM) and organic matter (OM) digestibility. When the ambient temperature increased from 15°C to 25°C, the DM and OM digestibility increased in animals fed Con silage, but decreased in animals fed Bm silage. Concomitantly, ME estimated from digestible nutrients was higher for Bm than for Con at 15°C, but no differences were found at 25°C and 35°C. Effects of diet by temperature interaction, furthermore, were observed for EE and CP digestibility. Therefore, forage quality has to be considered when feeding heat-stressed animals.     

Estimation of Energy Expenditure from Physical Activity Measures: Determinants of Accuracy

Objective: To describe the determinants, specifically age, body mass index, percentage of body fat, and physical activity (PA) level, associated with over‐ and underestimation of energy expenditure (EE) using PA records and the Stanford Seven‐Day Physical Activity Recall (7DR) compared with doubly labeled water (DLW). Research Methods and Procedures: We collected PA measures on 24 males eating a controlled diet designed to maintain body weight, and we determined EE from DLW and estimated EE from PA records and 7DR. Results: Absolute differences in the estimation of EE between DLW and PA assessment methods were greater for the 7DR (30.6 ± 9.9%) than PA records (7.9 ± 3.2%). In PA records, overestimation of EE was greater with older age and higher body fatness; EE was overestimated by 16.7% among men 50 years and older compared with only 5.3% among men <40 years of age. For percentage of body fat, EE was overestimated by 19.7% among men with a percentage of body fat ≥30% compared with only 5.6% among men with a percentage of body fat <25%. A trend for less overestimation of EE with higher levels of PA (measured by DLW/basal metabolic rate [BMR]) also was observed in the PA records. In the 7DR, the estimates of EE varied widely and no trends were observed by age, percentage of body fat, and PA levels. Discussion: Estimation of EE from the 7DR is considerably more variable than from PA records. Factors related to age and percentage of body fat influenced the accuracy of estimated EE in the PA record. Additional studies are needed to understand factors related to accurate reporting of PA behaviors, which are used to estimate EE in free‐living adults.     

Percent body fat via DEXA: comparison with a four-compartment model.

This study compared body composition by dual-energy X-ray absorptiometry (DEXA; Lunar DPX-L) with that via a four-compartment (4C; water, bone mineral mass, fat, and residual) model. Relative body fat was determined for 152 healthy adults [30.0 +/- 11.1 (SD) yr; 75.10 +/- 14.88 kg; 176.3 +/- 8.7 cm] aged from 18 to 59 yr. The 4C approach [20.7% body fat (%BF)] resulted in a significantly (P < 0.001) higher mean %BF compared with DEXA (18.9% BF), with intraindividual variations ranging from -2.6 to 7.3% BF. Linear regression and a Bland and Altman plot demonstrated the tendency for DEXA to progressively underestimate the %BF of leaner individuals compared with the criterion 4C model (4C %BF = 0.862 x DEXA %BF + 4.417; r(2) = 0.952, standard error of estimate = 1.6% BF). This bias was not attributable to variations in fat-free mass hydration but may have been due to beam-hardening errors that resulted from differences in anterior-posterior tissue thickness.